Current Views and Controversies in Auditory Processing Disorders. Current Guidelines and Status. Nature of APD ASHA, 2005

Transcription

1 Current Views and Controversies in Auditory Processing Disorders Rola Farah PhD Candidate The Department of Communication Sciences and Disorders University of Cincinnati Current Guidelines and Status The American Academy of Audiology British Society of Audiology Definition ASHA, 2005 (C)APD refers to difficulties in the perceptual processing of auditory information in the central nervous system (Central) Auditory Processing [(C)AP] refers to the efficiency and effectiveness by which the central nervous system (CNS) utilizes auditory information Nature of APD ASHA, 2005 Deficit in neural processing of auditory stimuli Deficit in the CANS per se Not due to higher order language, cognitive, or related factors May coexist with other disorders (e.g.,adhd, language impairment, and learning disability) Nature of APD BSA, 2011 APD has its origins in impaired neural function Auditory system afferent and efferent pathways Higher level processing systems - modulation APD No Gold Standard Gold standard defined: agreed clinical diagnostic standard with which h the sensitivity and specificity it of other measures can be compared BSA,

2 APD Diverse and Heterogeneous Auditory processing in the CNS Complex process Crossed and uncrossed pathways Serial and parallel processing Shared processing (other sensory/higher order) Diverse levels of impairment The Central Auditory Nervous System (CANS) Consists of nerve fibers and neural sites neural sites Function: Analysis and transfer of the electrical signal Ipsi and contralateral pathways Neural sites - CANS 1. Cochlear nucleus Probable role: refine the sound as it leaves the peripheral auditory system Ipsi and contralateral pathways 2. Superior olivary nucleus Probable role: locate the source of sound based on time and intensity differences from both ears CANS - cont. CANS - cont. 3. Lateral lemniscus Probable role: preservation of combined information from both ears 4. Inferior colliculus Probable role: communicate the information to other structures 5. Medial geniculate body Probable role: relay to cortex 6. Primary auditory cortex Hischl s gyrus (BA 41) Probable role: auditory discrimination and perception and connection to language association areas (recognition, interpretation, comprehension) 2

3 Overlapping Symptoms Screening for APD Non-modularity in the brain Cognitive memory attention Other sensory language Audition vision Overlapping symptoms Aim: to identify individuals at risk for APD Questionnaires: i not validated, d poor specificity, tend to over refer Other tests: SCAN:3 - screening (Keith, 2009) Research needed to develop valid screening tools SCAN-3 Screening form Candidates for APD Testing Children Listening complaints, learning problems, reading problems, or dyslexia, etc History of otitis media Hearing loss with complaints exceeding what is expected Adults Neurologic disease, disorder, or insult that affects auditory areas history of hyperbilrubinemia seizure disorders multiple sclerosis traumatic brain injury neurological conditions affecting the CANS General Considerations Pre- Testing Minimum age of seven or eight years (no normative data available for younger children) Use of speech and non-speech test stimuli Confounding factors: attention, motivation, cognitive status, hearing sensitivity and native language Test Consideration Administered by trained and skilled audiologist Choose the specific tests based on the individual s complaints - not test driven Examine different central auditory processes Choosing tests with known reliability and validity with normative data Know what is considered normal performance, age-wise Recommended test duration: min Assessment should include multi-disciplinary team 3

4 APD Assessment Comprehensive case history Questionnaires Peripheral hearing assessment Central auditory test battery APD Case History Crucial component Help determine the nature Illuminate the functional difficulties Must include: Family / genetic history Pre, peri, postnatal development Listening and auditory behaviors Educational status Therapies/treatments Common Symptoms AAA, 2010 Most common: Difficulty understanding speech in background noise or in reverberant acoustic environments Difficulty localizing the source of a signal Inappropriate responses Frequent requests for repetitions Difficulty following rapid speech Difficulty following directions Peripheral hearing Assessment Comprehensive audiometry Tympanometry y p y (rule out middle ear dysfunction) Otoacoustic emissions (rule out cochlear dysfunction) Central auditory Assessment Behavioral test battery Tests of Temporal Processes The ability to analyze acoustic events over time Dichotic Listening (Speech) Tests The ability to integrate or separate different auditory stimuli presented to both ears simultaneously Central Assessment cont. Tests of Monaural Low-Redundancy Speech Perception Recognition of speech stimuli presented monaurally in degraded way Auditory Discrimination Tests The ability to distinguish between similar acoustic stimuli that differ in frequency, intensity, or duration 4

5 Tests of Temporal Processes Temporal resolution Gaps-in-Noise (GIN) Test Sensitivity and specificity to cortical and brainstem lesions Random Gap Detection Test Temporal sequencing The Frequency (or Pitch) Pattern Sequence Test The Duration Patterns Test The Duration Patterns Test 1000 Hz tones Repeat the pattern verbally (S-S-L) Sensitive to cerebral lesion and dysfunctional corpus callosum Short 250 ms Short 250 ms 300 ms 300 ms Long 500 ms Dichotic Listening Tests Binaural Integration and Separation Dichotic digits Staggered Spondee Word Test (SSW) competing words Competing sentences Sensitive to cortical and interhemispheric lesions RIGHT TEMPORAL CORTEX Non-Dominant Hemisphere Right Ear Are Dichotic Test Procedure Corpus Callosum LEFT TEMPORAL CORTEX Primary Auditory Reception Area, Lang. Dominant Hemisphere Left Ear Cow The Dichotic Listening Test Procedure Competing Words SCAN:3 20 word pairs presented dichotically Count correct responses from Rt ear, then from Lt ear Ear advantage: correct Rt correct Lt Refer to normative data cow Are 5

6 Monaural Low-Redundancy Speech Perception Aim: Reduce the natural redundancy in speech signals using: High- or low-pass filtering Time compression Embedding speech in background noise Less sensitive to APD than other tests language and cognitive status might affect the results Localization and Lateralization Valid and commercially available tests are lacking Other Tests Auditory Discrimination Discrimination of: frequency, intensity and duration Valid and commercially available tests are lacking How to select the test battery? Test Battery Selection Tests targeting the individual s complaints Appropriate to the individual s age and cognitive status Assess different auditory processes Assess various regions and levels within the CANS Interpretation Performance must be compared to: Age-appropriate norms Performance across tests (Intertest analysis) APD Diagnosis: Poor performance (2 SD below the mean) on 2 or more tests in the battery Poor Performance (more than 3 SD) on 1 test Watch out for inconsistencies across tests might indicate non-auditory confounds The SCAN-3 Test Battery Keith, 2009 Contains the major tests recommended by position papers (ASHA, AAA). Normed on 775 subjects Provides Standardized scores, cut-off scores, Auditory composite score and prevalence of ear advantage for all tests Have the highest level of sensitivity and specificity of any auditory processing test or battery (Friburg & McNamara, 2010) 6

7 The SCAN-3 Test Battery Keith, 2009 Screening Tests Gap Detection examines temporal processing ability which may influence the ability to comprehend continues speech Auditory Figure Ground (+8dB) Tests ability to listen in background noise Competing Words (Free Recall) Dichotic listening task (poor performance may indicate lack of maturation or abnormality of the auditory nervous system) Diagnostic Tests Filtered Words tests the ability to process speech when distorted or compromised Competing Words (Directed Ear) Dichotic listening task that examines a child s auditory maturation Competing Sentences Provides information about the maturation of the CANS Supplementary Tests Auditory Figure Ground (+0 db and +12 db) Time Compressed Sentences Electroacoustic Measures DPOAEs TEOAEs Acoustic reflex thresholds and decay Aim: to differentiate between Cochlear and Retrocochlear Involvement Electrophysiologic measures Used to measure neuroelectrical activity from the auditory system when an individual is stimulated with sound Electrophysiologic measures Auditory Brainstem Response (ABR) Auditory Middle Latency Response (AMLR) Auditory Late Response (ALR) Auditory Brainstem Response (ABR) Information about the auditory nerve and brainstem pathways Early maturation of the response (18 months) Click-evoked ABR: limited sensitivity Speech-evoked ABR: recent promising method in diagnosing and monitoring intervention effects 7

8 Auditory Middle Latency Response (AMLR) Generators: thalamo-cortical pathways, primary auditory cortex Maturation: >10 years old Need to consider many interacting factors: stimulus rate, electrode effect, ear effect. No well-defined protocols for APD testing Auditory Late Response (ALR) Origins: both the primary and secondary auditory cortices Damage to the auditory cortex compromise the NI-P2 complex Age and stimulation rate can affect the response No well-defined protocols for APD testing The Mismatch Negativity (MMN) Used to test discrimination between similar acoustic stimuli Present in response to deviant stimulus in between frequent stimuli Elicited passively from individual Generators: primary and association auditory cortex, some frontal lobe regions When to use AEP s? Behavioral responses not conclusive Younger children Confounds by other factors Behavioral measures not available in native language To clarify site of dysfunction APD Diagnosis Once APD is diagnosed what is the next step? Intervention When: as soon as APD diagnosis is made and CANS is involved Aim: to exploit the brain s plasticity and cortical reorganization and to reduce functional deficits 8

9 Neural Plasticity The brain s ability to change; functionally and structurally in response to stimulation, deprivation or experience Intervention, Training & Plasticity Intensive intervention can cause formation of new neural networks by forming new connections between brain cells. Stimulation and practice can induce cortical reorganization leading to change in behavior Intervention Components Bottom-up Stimulus driven Auditory training Environmental modification assistive listening systems clear speech improved room acoustics Top-down Strategy driven Language & cognitive strategies t training i Instructional modifications Environment accommodations 1. Auditory training: Computer-based: Fast Forward Fast Forward Earobics LACE No documented research in APD Treatment Computer-based Auditory Training (CBAT) Engaging, multisensory stimulation Control specific deficits, task difficulty and training schedule Customized based on age & general cognitive state Key factors: Intensive training Deficit driven Task difficulty Auditory Training Abnormal findings of interhemispheric transfer based on pattern test and dichotic listening test results Dichotic Auditory Training (DAT) Multimodal exercises (e.g., linking emotion of facial expression to prosody of a message, sound-symbol association) 9

10 Auditory Training cont. Deficits identified on auditory performance in competition or degraded conditions Speech recognition in noise exercises to strengthen closure skills Other Treatment Options 2. FM systems: For deficits on monaural low-redundancy and/or dichotic speech tests (e.g., speech in noise, filtered or compressed speech) 3. Clear speech Slower rate, emphasizing key words, and pausing How do we examine plasticity changes? Effect Of Auditory Training kraus et.al., 1995 Improved behavioral scores Improved electrophysiological responses Improved functional ability Use neuroimaging techniques to monitor changes Selected References American Academy of Audiology, A. (2010). Guidelines for the Diagnosis, Treatment and Management of Children and Adults with Central Auditory Processing Disorder ([Task Force] - Available from American Speech Language Hearing Association, A. (2005). (Central) Auditory Processing Disorders ([ Technical Report ] Available at C ll T D Ki C K N M G T Ni l T & T bl K (1995 Carrell, T. D., King, C., Kraus, N., McGee, T., Nicol, T., & Tremblay, K. (1995, 1995 Winter). Central auditory system plasticity associated with speech discrimination training. Journal of Cognitive Neuroscience, 7, 25+. Friberg, J.C. & McNamara, T.L. (2010). Evaluating the reliability and validity of (Central) Auditory Processing Tests: A preliminary investigation. Journal of Educational Audiology, 2. Keith, R. W. (2009). SCAN-3 for Children. Tests of Auditory Processing Disorders. San Antonio: Pearson The British Society of Audiology and the UK APD Steering Group. (2011). from 10